<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <style>
        .mobile-bottom-nav {
            position: fixed;
            bottom: 0;
            left: 0;
            right: 0;
            height: 56px;
            background: #ffffff;
            display: flex;
            align-items: center;
            border-top: 1px solid #f0f0f0;
            box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.05);
            z-index: 1000;
            padding: 0 8px;
        }
        .nav-item {
            flex: 1;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            text-decoration: none;
            color: #666666;
            padding: 8px 0;
        }
        .nav-item.active {
            color: #ff4e50;
        }
        @media (min-width: 769px) {
            .mobile-bottom-nav {
                display: none;
            }
        }
    </style>
</head>
<body>
    <div class="mobile-bottom-nav">
        <a href="#" class="nav-item">首页</a>
        <a href="#" class="nav-item">收藏</a>
        <a href="#" class="nav-item">购物车</a>
        <a href="#" class="nav-item">我的</a>
    </div>
    
    <div style="height: 2000px; padding: 20px;">
        <h1>测试移动端底部导航</h1>
        <p>请调整浏览器窗口宽度小于769px来查看底部导航</p>
        <p>当前窗口宽度: <span id="width"></span>px</p>
    </div>

    <script>
        function updateWidth() {
            document.getElementById('width').textContent = window.innerWidth;
        }
        window.addEventListener('resize', updateWidth);
        updateWidth();
    </script>
</body>
</html>